An open question in our understanding of language processing and speech production is whether a common phonological lexicon within the brain serves both speech production and word recognition. Data from studies of patients with lesions provide conflicting evidence about the neural substrates mediating phonological access, supporting both the common lexicon and dual lexicons hypotheses. fMRI studies using Echo-planar imaging (EPI) will be performed in 10 right-handed subjects. Our fMRI study uses tasks that systematically evaluate both input and output phonological processing, and should help resolve the uncertainty about the number of phonological lexicons and their structure and function. Four tasks will be applied in these studies: Auditory discrimination, Rhyme judgments, Lexical decisions, and Synonym judgments. The project is funded by an NIH R03 (1/01/98 to 12/31/98). Preliminary studies have been performed to verify the operation of the auditory stimulus hardware. The initial studies performed in this project will likely lead to more comprehensive studies in the future. This research may result in a better understanding of the brain pathways involved in phonological access for speech production and for word recognition, and may contribute to a better understanding of language development and disorders.[unreadable]